UAW has been a stalwart supporter of the president and Obama has campaigned heavily on his decision to bail out the auto industry, particularly in the critical swing state of Ohio, where one in eight jobs depends on the industry.

Last week, Chrysler CEO Sergio Marchionne pushed back on a Romney ad that asserted the company was moving Jeep manufacturing to China. Gilles also pushed back on the assertion when it was made by Donald Trump last week. Gilles tweeted Trump "you are full of ----!"

UPDATE: Reuters' autos reporter Deepa Seetharaman points out this article from the New York Times, which says all auto workers were given Election Day off in contract negotiations several years ago, something the GOP was not happy about.

''That will be the biggest corporate contribution in American political history,'' Gov. John Engler of Michigan told the Times at the time, ''because the corporations will be paying the wages and the U.A.W. will be using the manpower to attempt to defeat Republican candidates.''